Relaxation and the Role of Calcium in Isolated Contracting Myocardium From Patients With Hypertensive Heart Disease and Heart Failure With Preserved Ejection Fraction

BackgroundRelaxation characteristics and Ca2+ homeostasis have not been studied in isolated myocardium from patients with hypertensive heart disease (HHD) and heart failure with preserved ejection fraction (HFpEF). Prolonged myocardial relaxation is believed to play an important role in the pathophysiology of these conditions. In this study, we evaluated relaxation parameters, myocardial calcium (Ca2+), and sodium (Na+) handling, as well as ion transporter expression and tested the effect of Na+-influx inhibitors on relaxation in isolated myocardium from patients with HHD and HFpEF. Methods and ResultsRelaxation characteristics were studied in myocardial strip preparations under physiological conditions at stimulation rates of 60 and 180 per minute. Intracellular Ca2+ and Na+ were simultaneously assessed using Fura-2 and AsanteNATRIUMGreen-2, whereas elemental analysis was used to measure total myocardial concentrations of Ca, Na, and other elements. Quantitative polymerase chain reaction was used to meas...